This invention relates generally to an apparatus and method for controlling a work implement of a work machine and, more particularly, to an apparatus and method for providing coordinated control of the work implement in order to produce linear movement of the work implement.
Work machines, such excavators, backhoe loaders, wheel loaders, telescopic material handlers, and the like, are adapted for digging, loading, pallet-lifting, etc. These operations usually require the use of two or more manually-operated control levers for controlling the position and orientation of the work implement.
As an example, a telescopic material handler includes a telescoping boom having a load-engaging member, e.g., pallet lifting forks, connected at one end of the boom. Two control levers are used to independently actuate hydraulic cylinders adapted for controlling the angle of the boom with respect to a reference plane, and the length of the boom, respectively.
Frequently, linear or straight-line movement of the forks are required, e.g., when the forks of the telescopic material handler are to be driven under a pallet in order to lift the pallet. In order to effect such linear movement, the angle of the boom and the length of the boom must be simultaneously controlled. Extensive operator skill is required for coordinating control of the levers while performing these complex operations, thus increasing operator fatigue for skilled operators, and the training time required for lesser skilled operators.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, an apparatus for providing coordinated control of a work implement of a work machine having a frame is disclosed. The implement includes a boom pivotally connected to the frame. The apparatus includes a boom position sensor adapted for providing a boom position signal, and an input device adapted for delivering a desired boom velocity signal indicative of the desired velocity of the boom. The desired velocity includes a desired angular velocity and a desired linear velocity. The apparatus receives the boom position signal and the desired boom velocity signal, and determines an actual velocity of the boom as a function of the boom position signal. The apparatus further compares the actual velocity of the boom and the desired velocity of the boom, and modifies the desired angular velocity and the desired linear velocity in response to a difference between the desired and actual velocities of the boom.
In another aspect of the present invention, a method for providing coordinated control of a work implement of a work machine is disclosed. The method includes the steps of sensing a position of the boom, and responsively delivering a boom position signal. The method also includes the step of delivering a desired boom velocity signal indicative of the desired velocity of the boom, the desired velocity including a desired angular velocity and a desired linear velocity. The method further includes the steps of determining an actual velocity of the boom as a function of the boom position signal, comparing the actual velocity of the boom and the desired velocity of the boom, and modifying the desired angular velocity and the desired linear velocity in response to a difference between the actual and desired velocities of the boom.